diff --git a/src/net/api_client.gd b/src/net/api_client.gd
new file mode 100644
index 0000000..ed8ebbf
--- /dev/null
+++ b/src/net/api_client.gd
@@ -0,0 +1,170 @@
+class_name ApiClient
+extends Node
+
+## T-WIN-002：Web 服务端 REST 客户端
+##
+## 只消费 opendance-web 冻结的契约（contracts/rest-api.yaml v0.1.0）。
+## 所有方法返回 { ok: bool, status: int, data: Variant, error: String }，
+## 不抛异常，调用方统一判 ok。
+
+signal request_completed(path: String, ok: bool, status: int)
+
+const DEFAULT_TIMEOUT_SECONDS := 20.0
+
+var base_url: String = "http://127.0.0.1:3000"
+var timeout_seconds: float = DEFAULT_TIMEOUT_SECONDS
+
+
+func _init(api_base_url: String = "") -> void:
+	if api_base_url != "":
+		base_url = api_base_url
+
+
+## 规范化基地址：去掉尾部斜杠
+func set_base_url(value: String) -> void:
+	base_url = value.strip_edges().rstrip("/")
+
+
+static func join_url(base: String, path: String) -> String:
+	var b := base.rstrip("/")
+	var p := path if path.begins_with("/") else "/" + path
+	return b + p
+
+
+func get_json(path: String) -> Dictionary:
+	return await _request(HTTPClient.METHOD_GET, path)
+
+
+func get_text(path: String) -> Dictionary:
+	return await _request(HTTPClient.METHOD_GET, path, {}, true)
+
+
+## 下载二进制资源（模型文件等）
+func get_binary(path: String) -> Dictionary:
+	return await _request(HTTPClient.METHOD_GET, path, {}, false, true)
+
+
+func post_json(path: String, body: Dictionary = {}) -> Dictionary:
+	return await _request(HTTPClient.METHOD_POST, path, body)
+
+
+## 健康检查：契约 GET /health
+func health() -> Dictionary:
+	return await get_json("/health")
+
+
+## 契约版本 + 目录指纹：GET /api/catalog/version
+func catalog_version() -> Dictionary:
+	return await get_json("/api/catalog/version")
+
+
+## 客户端一次性拉取已发布目录：GET /api/catalog/export
+func catalog_export() -> Dictionary:
+	return await get_json("/api/catalog/export")
+
+
+## 关键点序列（NDJSON）：GET /api/motions/{id}/keypoints
+func motion_keypoints(motion_id: int) -> Dictionary:
+	return await get_text("/api/motions/%d/keypoints" % motion_id)
+
+
+func _request(method: int, path: String, body: Dictionary = {}, as_text: bool = false, as_binary: bool = false) -> Dictionary:
+	var outcome := {
+		"ok": false,
+		"status": 0,
+		"data": null,
+		"error": "",
+	}
+
+	var http := HTTPRequest.new()
+	http.timeout = timeout_seconds
+	add_child(http)
+
+	var url := join_url(base_url, path)
+	var headers := PackedStringArray(["Accept: application/json"])
+	var payload := ""
+	if method != HTTPClient.METHOD_GET:
+		payload = JSON.stringify(body)
+		headers.append("Content-Type: application/json")
+
+	var err := http.request(url, headers, method, payload)
+	if err != OK:
+		outcome["error"] = "无法发起请求（错误码 %d）：%s" % [err, url]
+		http.queue_free()
+		request_completed.emit(path, false, 0)
+		return outcome
+
+	var response: Array = await http.request_completed
+	http.queue_free()
+
+	var result_code: int = response[0]
+	var status: int = response[1]
+	var raw: PackedByteArray = response[3]
+	outcome["status"] = status
+
+	if result_code != HTTPRequest.RESULT_SUCCESS:
+		outcome["error"] = _describe_result(result_code)
+		request_completed.emit(path, false, status)
+		return outcome
+
+	var text := raw.get_string_from_utf8()
+	if status < 200 or status >= 300:
+		outcome["error"] = "服务端返回 %d：%s" % [status, _extract_error_message(text)]
+		request_completed.emit(path, false, status)
+		return outcome
+
+	if as_binary:
+		outcome["ok"] = true
+		outcome["data"] = raw
+		request_completed.emit(path, true, status)
+		return outcome
+
+	if as_text:
+		outcome["ok"] = true
+		outcome["data"] = text
+		request_completed.emit(path, true, status)
+		return outcome
+
+	var parsed: Variant = JSON.parse_string(text)
+	if parsed == null and text.strip_edges() != "null":
+		outcome["error"] = "响应不是合法 JSON"
+		request_completed.emit(path, false, status)
+		return outcome
+
+	outcome["ok"] = true
+	outcome["data"] = parsed
+	request_completed.emit(path, true, status)
+	return outcome
+
+
+## 解析契约统一错误体 { statusCode, message, error }
+static func _extract_error_message(text: String) -> String:
+	var parsed: Variant = JSON.parse_string(text)
+	if typeof(parsed) != TYPE_DICTIONARY:
+		return text.strip_edges().left(200)
+	var dict: Dictionary = parsed
+	if not dict.has("message"):
+		return text.strip_edges().left(200)
+	var message: Variant = dict["message"]
+	if typeof(message) == TYPE_ARRAY:
+		var parts := PackedStringArray()
+		for item in message:
+			parts.append(str(item))
+		return "; ".join(parts)
+	return str(message)
+
+
+static func _describe_result(code: int) -> String:
+	match code:
+		HTTPRequest.RESULT_CANT_CONNECT:
+			return "无法连接到服务端（请确认 Web 服务端已启动且地址正确）"
+		HTTPRequest.RESULT_CANT_RESOLVE:
+			return "无法解析服务端地址"
+		HTTPRequest.RESULT_CONNECTION_ERROR:
+			return "连接中断"
+		HTTPRequest.RESULT_TIMEOUT:
+			return "请求超时"
+		HTTPRequest.RESULT_TLS_HANDSHAKE_ERROR:
+			return "TLS 握手失败"
+		_:
+			return "请求失败（结果码 %d）" % code
diff --git a/src/net/catalog_types.gd b/src/net/catalog_types.gd
new file mode 100644
index 0000000..4bfc0c6
--- /dev/null
+++ b/src/net/catalog_types.gd
@@ -0,0 +1,235 @@
+class_name CatalogTypes
+extends RefCounted
+
+## 契约资源类型 —— contracts/data-models.md v0.1.0
+## 字段名与 JSON 完全一致（camelCase），解析时做类型收敛。
+
+## 来源（出处）五元组 —— 契约 §1
+class SourceInfo extends RefCounted:
+	var source_type: String = ""
+	var source_name: String = ""
+	var source_url: String = ""
+	var license: String = ""
+	var author: String = ""
+
+	static func from_dict(d: Dictionary) -> SourceInfo:
+		var out := SourceInfo.new()
+		out.source_type = str(d.get("sourceType", ""))
+		out.source_name = str(d.get("sourceName", ""))
+		out.source_url = str(d.get("sourceUrl", ""))
+		out.license = str(d.get("license", ""))
+		out.author = str(d.get("author", ""))
+		return out
+
+	## 来源类型的中文标签（管理/展示用）
+	func type_label() -> String:
+		match source_type:
+			"original": return "原创"
+			"licensed": return "已获授权"
+			"cc": return "Creative Commons"
+			"public_domain": return "公共领域"
+			"user_upload": return "用户上传"
+			"other": return "其他"
+		return source_type
+
+	## 是否五项齐备 —— 契约要求任何资产都必须完整
+	func is_complete() -> bool:
+		return (
+			source_type != "" and source_name != "" and source_url != ""
+			and license != "" and author != ""
+		)
+
+
+class Song extends RefCounted:
+	var id: int = 0
+	var title: String = ""
+	var artist: String = ""
+	var album: String = ""
+	var language: String = ""
+	var duration_ms: int = 0
+	var bpm: float = 0.0
+	var difficulty: int = 0
+	var tags: PackedStringArray = PackedStringArray()
+	var cover_url: String = ""
+	var audio_url: String = ""
+	var source: SourceInfo = SourceInfo.new()
+	var status: String = ""
+
+	static func from_dict(d: Dictionary) -> Song:
+		var out := Song.new()
+		out.id = int(d.get("id", 0))
+		out.title = str(d.get("title", ""))
+		out.artist = str(d.get("artist", ""))
+		out.album = str(d.get("album", "") if d.get("album") != null else "")
+		out.language = str(d.get("language", "") if d.get("language") != null else "")
+		out.duration_ms = int(d.get("durationMs", 0) if d.get("durationMs") != null else 0)
+		out.bpm = float(d.get("bpm", 0.0) if d.get("bpm") != null else 0.0)
+		out.difficulty = int(d.get("difficulty", 0) if d.get("difficulty") != null else 0)
+		out.tags = CatalogTypes._strings(d.get("tags", []))
+		out.cover_url = CatalogTypes._nullable_string(d.get("coverUrl"))
+		out.audio_url = CatalogTypes._nullable_string(d.get("audioUrl"))
+		out.source = SourceInfo.from_dict(d)
+		out.status = str(d.get("status", ""))
+		return out
+
+	func duration_label() -> String:
+		if duration_ms <= 0:
+			return "--:--"
+		var total := int(duration_ms / 1000.0)
+		return "%d:%02d" % [total / 60, total % 60]
+
+
+class Motion extends RefCounted:
+	var id: int = 0
+	var song_id: int = -1
+	var name: String = ""
+	var format: String = ""
+	var file_url: String = ""
+	var file_size: int = 0
+	var fps: float = 0.0
+	var frame_count: int = 0
+	var duration_ms: int = 0
+	var keypoint_format: String = ""
+	var keypoint_url: String = ""
+	var keypoint_frames: int = 0
+	var preprocess_state: String = "none"
+	var preprocess_error: String = ""
+	var source: SourceInfo = SourceInfo.new()
+	var status: String = ""
+
+	static func from_dict(d: Dictionary) -> Motion:
+		var out := Motion.new()
+		out.id = int(d.get("id", 0))
+		out.song_id = int(d.get("songId", -1) if d.get("songId") != null else -1)
+		out.name = str(d.get("name", ""))
+		out.format = str(d.get("format", ""))
+		out.file_url = CatalogTypes._nullable_string(d.get("fileUrl"))
+		out.file_size = int(d.get("fileSize", 0) if d.get("fileSize") != null else 0)
+		out.fps = float(d.get("fps", 0.0) if d.get("fps") != null else 0.0)
+		out.frame_count = int(d.get("frameCount", 0) if d.get("frameCount") != null else 0)
+		out.duration_ms = int(d.get("durationMs", 0) if d.get("durationMs") != null else 0)
+		out.keypoint_format = CatalogTypes._nullable_string(d.get("keypointFormat"))
+		out.keypoint_url = CatalogTypes._nullable_string(d.get("keypointUrl"))
+		out.keypoint_frames = int(d.get("keypointFrames", 0) if d.get("keypointFrames") != null else 0)
+		out.preprocess_state = str(d.get("preprocessState", "none"))
+		out.preprocess_error = CatalogTypes._nullable_string(d.get("preprocessError"))
+		out.source = SourceInfo.from_dict(d)
+		out.status = str(d.get("status", ""))
+		return out
+
+	## 是否可用于 DTW 参考序列
+	func is_scorable() -> bool:
+		return preprocess_state == "done" and keypoint_frames > 0
+
+	func preprocess_label() -> String:
+		match preprocess_state:
+			"none": return "未处理"
+			"running": return "处理中"
+			"done": return "已完成"
+			"failed": return "失败"
+		return preprocess_state
+
+
+class Model extends RefCounted:
+	var id: int = 0
+	var name: String = ""
+	var format: String = ""
+	var vrm_version: String = ""
+	var is_primary: bool = false
+	var file_url: String = ""
+	var file_size: int = 0
+	var thumbnail_url: String = ""
+	var source: SourceInfo = SourceInfo.new()
+	var status: String = ""
+
+	static func from_dict(d: Dictionary) -> Model:
+		var out := Model.new()
+		out.id = int(d.get("id", 0))
+		out.name = str(d.get("name", ""))
+		out.format = str(d.get("format", ""))
+		out.vrm_version = CatalogTypes._nullable_string(d.get("vrmVersion"))
+		out.is_primary = bool(d.get("isPrimary", false))
+		out.file_url = CatalogTypes._nullable_string(d.get("fileUrl"))
+		out.file_size = int(d.get("fileSize", 0) if d.get("fileSize") != null else 0)
+		out.thumbnail_url = CatalogTypes._nullable_string(d.get("thumbnailUrl"))
+		out.source = SourceInfo.from_dict(d)
+		out.status = str(d.get("status", ""))
+		return out
+
+	func is_vrm() -> bool:
+		return format == "vrm"
+
+
+## 契约 §6：客户端一次性拉取的目录
+class CatalogBundle extends RefCounted:
+	var songs: Array = []
+	var motions: Array = []
+	var models: Array = []
+	var default_model_id: int = -1
+	var contract_version: Dictionary = {}
+	var generated_at: String = ""
+
+	static func from_dict(d: Dictionary) -> CatalogBundle:
+		var out := CatalogBundle.new()
+		for item in d.get("songs", []):
+			out.songs.append(Song.from_dict(item))
+		for item in d.get("motions", []):
+			out.motions.append(Motion.from_dict(item))
+		for item in d.get("models", []):
+			out.models.append(Model.from_dict(item))
+		var default_id: Variant = d.get("defaultModelId")
+		out.default_model_id = int(default_id) if default_id != null else -1
+		out.contract_version = d.get("contractVersion", {})
+		out.generated_at = str(d.get("generatedAt", ""))
+		return out
+
+	func find_song(id: int) -> Song:
+		for song in songs:
+			if song.id == id:
+				return song
+		return null
+
+	func find_motion(id: int) -> Motion:
+		for motion in motions:
+			if motion.id == id:
+				return motion
+		return null
+
+	func find_model(id: int) -> Model:
+		for model in models:
+			if model.id == id:
+				return model
+		return null
+
+	func motions_for_song(song_id: int) -> Array:
+		var out: Array = []
+		for motion in motions:
+			if motion.song_id == song_id:
+				out.append(motion)
+		return out
+
+	## 契约 §4.1：默认模型由服务端解析好，客户端直接用 defaultModelId
+	func default_model() -> Model:
+		var model := find_model(default_model_id)
+		if model != null:
+			return model
+		for candidate in models:
+			if candidate.is_vrm():
+				return candidate
+		return models[0] if models.size() > 0 else null
+
+
+# ---------------- 解析辅助 ----------------
+
+static func _strings(value: Variant) -> PackedStringArray:
+	var out := PackedStringArray()
+	if typeof(value) == TYPE_ARRAY:
+		for item in value:
+			out.append(str(item))
+	return out
+
+
+static func _nullable_string(value: Variant) -> String:
+	if value == null:
+		return ""
+	return str(value)
diff --git a/src/net/keypoint_sequence.gd b/src/net/keypoint_sequence.gd
new file mode 100644
index 0000000..737fa57
--- /dev/null
+++ b/src/net/keypoint_sequence.gd
@@ -0,0 +1,129 @@
+class_name KeypointSequence
+extends RefCounted
+
+## 参考关键点序列 —— 契约 contracts/model-formats.md §2.1
+##
+## 服务端 T-WEB-006 预处理产出的 NDJSON，每行一帧：
+##   {"frame":0,"timeMs":0.0,"points":[[x,y,z,conf] × 33],"angles":[9 个余弦]}
+##
+## 本类把它解析为与实时链路**同构**的 PoseFeatures.FeatureVector 序列，
+## 使 DTW 引擎只有一条输入通路（契约 skeleton-topology.md §5 的设计意图）。
+
+const KeypointFrame = preload("res://src/net/keypoint_frame.gd")
+const PoseFeatures = preload("res://src/score/pose_features.gd")
+
+## 服务端产出的 keypointFormat 标识，必须完全匹配
+const EXPECTED_FORMAT := "mediapipe33@0.1.0"
+
+
+class ParsedSequence extends RefCounted:
+	## Array[KeypointFrame.PoseFrame]
+	var frames: Array = []
+	## Array[PoseFeatures.FeatureVector]
+	var features: Array = []
+	## Array[PackedFloat32Array]，服务端算好的 9 个关节角（用于交叉校验）
+	var server_angles: Array = []
+	var times_ms: PackedFloat32Array = PackedFloat32Array()
+	var skipped_lines: int = 0
+
+	func frame_count() -> int:
+		return frames.size()
+
+	func duration_ms() -> float:
+		if times_ms.is_empty():
+			return 0.0
+		return times_ms[times_ms.size() - 1]
+
+	## 依据时间戳推导源帧率
+	func estimated_fps() -> float:
+		if times_ms.size() < 2:
+			return 30.0
+		var span := times_ms[times_ms.size() - 1] - times_ms[0]
+		if span <= 0.0:
+			return 30.0
+		return float(times_ms.size() - 1) / (span / 1000.0)
+
+
+## 解析 NDJSON；失败时返回 frames 为空的序列，并把原因写入 error
+static func parse_ndjson(text: String) -> ParsedSequence:
+	var out := ParsedSequence.new()
+	if text.strip_edges() == "":
+		return out
+
+	var line_number := 0
+	for raw_line in text.split("\n"):
+		line_number += 1
+		var line := raw_line.strip_edges()
+		if line == "":
+			continue
+
+		var parsed: Variant = JSON.parse_string(line)
+		if typeof(parsed) != TYPE_DICTIONARY:
+			out.skipped_lines += 1
+			continue
+
+		var frame := _frame_from_dict(parsed)
+		if frame == null:
+			out.skipped_lines += 1
+			continue
+
+		out.frames.append(frame)
+		out.features.append(PoseFeatures.build(frame))
+		out.server_angles.append(_angles_from_dict(parsed))
+		out.times_ms.append(float(parsed.get("timeMs", 0.0)))
+
+	return out
+
+
+static func _frame_from_dict(data: Dictionary) -> KeypointFrame.PoseFrame:
+	var raw_points: Array = data.get("points", [])
+	if raw_points.size() != KeypointFrame.KEYPOINT_COUNT:
+		return null
+
+	var frame := KeypointFrame.PoseFrame.new()
+	frame.frame_id = int(data.get("frame", 0))
+	frame.points.resize(KeypointFrame.KEYPOINT_COUNT)
+	frame.confidence.resize(KeypointFrame.KEYPOINT_COUNT)
+
+	for i in KeypointFrame.KEYPOINT_COUNT:
+		var entry: Variant = raw_points[i]
+		if typeof(entry) != TYPE_ARRAY or (entry as Array).size() != 4:
+			return null
+		var point: Array = entry
+		frame.points[i] = Vector3(float(point[0]), float(point[1]), float(point[2]))
+		frame.confidence[i] = float(point[3])
+
+	return frame
+
+
+static func _angles_from_dict(data: Dictionary) -> PackedFloat32Array:
+	var out := PackedFloat32Array()
+	var raw: Variant = data.get("angles", [])
+	if typeof(raw) == TYPE_ARRAY:
+		for value in raw:
+			out.append(float(value))
+	return out
+
+
+## 校验服务端 angles 与本端 PoseFeatures 计算结果是否一致（跨实现交叉校验）
+## 返回 { max_delta, mismatched_frames, checked }
+static func compare_angles(sequence: ParsedSequence, tolerance: float = 1e-3) -> Dictionary:
+	var max_delta := 0.0
+	var mismatched := 0
+	var checked := 0
+	for i in sequence.features.size():
+		var server: PackedFloat32Array = sequence.server_angles[i]
+		if server.size() != PoseFeatures.ANGLE_COUNT:
+			continue
+		var local: PoseFeatures.FeatureVector = sequence.features[i]
+		var frame_ok := true
+		for a in PoseFeatures.ANGLE_COUNT:
+			var local_value: float = local.values[PoseFeatures.KEYPOINT_COUNT * 3 + a]
+			var delta := absf(local_value - server[a])
+			max_delta = maxf(max_delta, delta)
+			if delta > tolerance:
+				frame_ok = false
+		checked += 1
+		if not frame_ok:
+			mismatched += 1
+	return {"max_delta": max_delta, "mismatched_frames": mismatched, "checked": checked}